eLetters

896 e-Letters

  • Iron deficiency and infective endocarditis

    The point is well made(even in passing) that iron deficient heart failure patients assigned to treatment with intravenous iron experience significantly lower rates of infection than counterparts not allocated to that treatment modality[1]. Even outside the context of congestive heart failure(CHF) iron deficiency has been shown to be associated with increased risk of infection[2]. The latter study explored the risk of infection according to levels of serum iron, transferrin saturation(TS), and serum ferritin. After multivariate adjustment, low TS at or below the fifth percentile(ie TS 11% or below) was associated with increased risk of any infection compared with TS between the 26th and the 74th percentile(ie TS 18.1-27.9)(Hazard Ratio 1.18; 95% Confidence Interval 1.10-1.26). More specifically, in that study , where >90% of infection-related deaths were attributable to pneumonia, low TS was also associated with increased risk of pneumonia(Hazard Ratio 1.20;95% CI 1.09-1.32)[2]..
    In the cardiology context, infective endocarditis(IE), a disorder often complicated by CHF, can, itself, occur in association with iron deficiency(ID).
    The following are examples of the association of IE and ID:-
    (i)Association of IE and nutritional ID was documented in a 19 year old woman with a history of volitional anorexia and wight loss.

    Iron deficiency was characterised by TS of 10%. She was initially given a diagnosis of anorexia nervosa and was pr...

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  • Response to "Gaps in knowledge and management of iron deficiency in heart failure: a nationwide survey of cardiologists in China "

    Bridging the Gap: Improving Iron Deficiency Management in Heart Failure
    The article by Su et al. offers an in-depth exploration of the persistent gaps in the knowledge and management of iron deficiency (ID) among cardiologists treating heart failure (HF) patients in China. This study not only highlights deficiencies in adherence to evidence-based guidelines but also underscores systemic and educational barriers that hinder optimal care.

    The findings are striking: over half of the cardiologists surveyed were unaware of the need to routinely screen for ID in HF patients, and only a fraction understood the critical diagnostic role of transferrin saturation (TSAT). Alarmingly, less than 1% identified TSAT <20% as a standalone criterion for diagnosing ID, despite its established prognostic significance. This lack of awareness reflects a larger, global challenge in implementing ID management protocols, which are consistently linked to improved outcomes in HF patients.

    Equally concerning is the predominant reliance on oral iron supplementation, with 68% of respondents favoring it over intravenous (IV) iron. This preference persists despite robust evidence from clinical trials demonstrating the superior efficacy of IV iron in improving functional capacity, quality of life, and reducing HF hospitalizations. Barriers to IV iron use—ranging from limited availability of recommended formulations like ferric carboxymaltose to misconceptions about adverse effects—f...

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  • Professor

    To the editor: Zhang et al. provide a fascinating observational study showing that weight loss among obese UK Biobank participants with cardiovascular disease may not be beneficial [1]. The authors specifically highlight the following point “Maintaining a stable weight in obese people with cardiovascular disease may reduce the risk of mortality” [1]. Evidence from a large trial has shown that the weight loss drug semaglutide reduces mortality amongst the overweight/obese with pre-existing cardiovascular disease [2]. It is possible that some of the benefits of semaglutide could be driven by factors other than weight loss, given some benefits are evident before substantial weight has occurred [2]. However, some of the benefits of semaglutide are undoubtedly due to weight loss making Zhang et al.’s observations puzzling.

    Zhang at al.’s study is an observational study of weight change in obese people with cardiovascular disease [1], so it is essentially a case series. Inference from case series is seen as the least reliable type of observational evidence [3]. Correspondingly, Zhang et al.’s study of the role of weight change in obese people with cardiovascular disease [1] is open to both the major sources of bias in causal inference, i.e., to confounding and selection bias [4].

    Specifically, Zhang et al.’s study is open to confounding by obesity because obesity is likely a common cause of weight change and death. The study is also open to selection bias because...

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  • Invalid methodology

    Economou Lundeberg et al report a U-shaped association between individuals estimated sodium intake and premature ventricular complexes (1). The estimate of individual sodium intake is based on a single fasting spot urine sodium value and the Kawasaki formula (1). The authors claim that the method is valid in part because the urine samples were collected in the fasting state and that the results have a correlation with 24-hr urine sodium excretion and blood pressure (1).

    However, extensive consistent evidence, as repeatedly reviewed by major international scientific organizations, indicates single spot urine sodium values with estimating equations (including those using fasting urine samples and the Kawasaki equation) are not a valid method of assessing an individual’s dietary sodium (2-4). The method has very high random and systematic errors (2, 4, 5). The systematic errors have been shown to alter a linear association of dietary sodium and health outcomes (blood pressure and cardiovascular disease) including to a U or J shaped curve and to have associations with health outcomes when a constant sodium value is inserted in the equation rather than a real value (2-5). The changes in disease associations and disease associations independent of the sodium variable have been shown in several data bases and are mathematically predictable.

    The random error is reflected by very low accuracy and reproducibility. For example, in a reanalysis of the validation of...

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  • The special case for low-dose edoxaban

    Given the disparity between the number of patients in apixaban(4261 patients) and the number of patients on edoxaban(76 patients)[1] it was not possible to make a meaningful comparison between the two agents especially because, in other contexts, edoxaban has been utilised in doses ranging from 15 mg/day to 6o mg/day in people with atrial fibrillation(AF){2],{3]. Accordingly, to lump edoxaban with other direct oral anticoagulants(DOACS) in the comparison with warfarin, as Mitchell et al have done(fig 4)[1[] does not do justice to the safety profile of edoxaban.
    In the comparison undertaken by Eikelboom et al between the safety profile of warfarin and individual DOACs the 30 mg/day dose of edoxaban was cited as being associated with significantly lower risk of gastrointestinal bleeding than warfarin(Hazard Ratio 0.67; 95% Confidence Interval 0.53-0.83)[2]. This was the dose recommended in patients with body weight 60 kg or less[2].
    In the ELDERCARE-AF randomised clinical care comprising 984 atrial fibrillation patients of mean age 86 a comparison was made between edoxaban 15 mg/day versus placebo. Edoxaban was associated with significantly lower rates of stroke and systemic embolism than placebo, both in frail elderly patients(p=0.02 ) and in non frail elderly(p=0.002), respectively.
    References
    [1]Mitchell A., Watson M., Welsh TJ., McGrogan A
    Safety and effectiveness of anticoagulation therapy in older people with atrial fibrillation d...

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  • There may also be an overlap with idiopathic giant cell myocarditis

    Due to the considerable degree of overlap between stigmata of cardiac sarcoidosis(CS) and idiopathic giant cell myocarditis(IGCM)[1], an evaluation of the association of CS and arrhythmogenic cardiomyopathy(ACM)[2] should be accompanied by a caveat acknowledging the potential for an association along the same lines also to exist between ACM and IGCM. The evidence which supports such an association is to be found in the study which showed a reduction in immunoreactive signal for the desmosomal protein plakoglobin at the cardiac myocyte junctions not only in patients with CS but, also, in patients with IGCM[3].
    The following are some of the parallels between CS, IGCM, and ACM:-
    (i)The atrioventricular(AV) conduction derangements which characterise the association of CS and ACM[2] have , as their counterpart, the AV conduction defects documented in CS and in IGCM, respectively[4], and also in ACM, on its own.{5].
    (ii)Interventricular septum involvement documented in some of the patients with the association of CS and ACM[2] has, as its counterpart, interventricular septal infiltration by IGCM[6], and by ACM[7].
    (iii)Finally, extensive myocardial fibrosis, sometimes associated with concomitant replacement of myocardium by adipocytes, may be a feature of CS[8]. It may also be a feature of IGCM(without concomitant adipocyte infiltration)[9], and may be a feature of ACM even in the absence of concomitant adipocyte infiltration[10].
    For all t...

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  • atrial fibrillation as a comorbidity

    No evaluation of clot-in-transit would be complete without a recognition of
    the triangular relationship between atrial fibrillation(AF), right heart
    thrombi(RHT), and pulmonary embolism(PE).

    On the one hand, AF(by causing stasis of right atrial blood) is a risk factor for
    PE[1]. This can be inferred from the documentation of PE in patients who have
    AF in the absence of concurrent deep vein thrombosis(DVT)[2]. On the other
    hand, PE is a risk factor for subsequent development of AF[1]. Anecdotal
    reports reinforce these observations. In one report. A 70 year old patient with
    PE presented with recent onset breathlessness in association with
    echocardiographic documentation of right atrial thrombus. During the time
    course of the same echocardiographic evaluation the thrombus was seen to
    migrate from the right atrium to the right pulmonary artery. Further imaging
    by computed tomography pulmonary angiography(CTPA) was deemed
    unnecessary, presumably because the RHT had reached its final destination.

    These observations have the potential to generate fundamental differences in
    the approach to the workup of patients with the association of symptoms of PE
    and documentation of the presence of clots either in the deep veins or in the
    right heart chambers. According to one school of thought the aim of
    echocardiography is merely “to support the clinical suspicion of pulmonary

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  • Triangular relationship between biomarkers, renal function and atrial fibrillation

    No evaluation of the association between NT-pro BNP levels and risk of atrial fibrillation(AF) can ever be complete without a recognition of the triangular relationship between AF, renal function, and natriuretic peptide levels.
    The starting point is a recognition that impairment of renal function is a risk factor for incident AF(and vice versa) and that a fall in glomerular filtration rate is associated with an increase in NT-pro BNP levels.
    The formula for estimated glomerular filtration rate(eGFR) which most accurately shows that impairment of eGFR confers higher risk of incident AF is the one that utilises the difference between cystatin C-based eGFR and creatinine-based eGFR[1]. In the latter study, during a median follow up of 11.7 years, it was shown that participants with impaired eGFR had a higher risk of incident AF(subdistirbution Hazard Ratio 1.25; 95% Confidence Interval 1.20 to 1.30)[1]. Using the same formula, other workers showed that prevalent AF was associated with increased risk of incident reduction in renal function(adjusted HR 1.33;95% CI 1.12 to 1.58)[2].
    Secondly, there is an association between renal function and natriuretic peptide levels, most likely as a consequence of the fact that 55%-65% of plasma NT pro BNP is cleared by the kidney[3]. Consequently, renal clearance of NT pro BNP is markedly decreased in chronic kidney disease(CKD)[4]. For example, among patients on chronic haemodialysis, eGFR has been shown to be i...

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  • Broadening the differential diagnosis of TTC-related mitral regurgitation

    Intriguingly, in the recent study, severe mitral regurgitation was present in as many as 10.3% of patients who did not have left ventricular outflow tract obstruction(LVOTO)[1]. This observation raises the question of whether or not mitral regurgitation(MR) might, in some of those cases, have been attributable to Takotsubo-related tethering of the mitral valve leaflets[2]. The latter was the underlying cause of severe MR in a 57 year old woman with previous history of treated hypertension who presented with chest pain and a blood pressure of 119/84 mm Hg. What we do not know is whether or not that blood pressure was her usual "on treatment" blood pressure or whether it represented a significant fall from her usual blood pressure. Her electocardiogram(ECG) showed ST segment elevation in leads V5 and V6. Coronary angiography did not show any obstructive lesion. Instead, she had stigmata of TTC, namely, apical left ventricular apical hypokinesis and basal hyperkinesis. Furthermore, she had eccentric mitral regurgitation associated with tethering of the anterior mitral leaflet. Neither LVOTO nor systolic anterior motion(SAM) of the mitral valve was observed. Her left ventricular ejection fraction(LVEF) amounted to 59.7%. After an uneventful clinical course she had a follow up which showed complete resolution of MR[2]. Leaflet tethering is believed also to be implicated in the aetiopathogenesis of TTC-related tricuspid regurgitation(TR)[3]. On occasions...

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  • SCD linked to multiple variables and risk factors

    The health and wellbeing of an individual are shaped by many factors. Although this valuable study (1) focusses on elevated risk of sudden cardiac death (SCD) in patients with psychiatric disorders, and adjusts for age, sex and comorbidities, multiple other variables and risk factors were not considered; these may be outside of the remit of this study.
    Multiple variables and multiple other risk factors may interact, and interplay, all of which could affect the outcome of SCD in patients with psychiatric disorders. These include genetic factors, family history of cardiovascular disease and a personal history of cardiovascular diseases. Multiple cardiometabolic risk factors (risk factors include hypertension, diabetes, elevated cholesterol/ lipid levels and smoking) predisposes individuals to SCD.
    The health of respiratory system and other vital organs (liver, kidneys, gut health) can modulate or indirectly affect cardiometabolic disease, which can lead to SCD. For example, COPD have a 34% increased risk of SCD overall, but the risk almost doubles more than five years after first being diagnosed with COPD. The risk of SCD increases more than three-fold after five years, in COPD patients who have frequent exacerbations (2).
    Although the above-named risk factors shape the outcome of cardiovascular diseases and SCD, the most important variables are related to the social determinants of health (SDH). The health and wellbeing of an individual are shaped by SDH....

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